Numerous chair designs have been proposed with a back structure retained to pivot in relation to a seat structure by a pivoting mechanism. Under certain constructions, the resistance provided by the pivoting mechanism cannot be adjusted. With this, large users, small users, and users with different preferences are provided with identical pivoting resistance. Consequently, lighter users may find that a chair provides far too much resistance while heavier users are likely to find that the same chair provides insufficient support against pivoting.
In other constructions, the resistance provided by the pivoting mechanism can be adjusted over a given range of resistance. With this, a user can seek to adjust the resistance provided by the pivoting mechanism to suit his or her physical characteristics and personal preferences. However, the range over which the pivoting mechanism is adjustable is commonly limited so that not all users will be accommodated even where the full range of adjustment is exploited. Furthermore, the adjustable pivoting mechanisms of the prior art typically require a continuous adjustment through the range of pivoting resistance. For example, many arrangements require that the user adjust the pivoting resistance by continuous rotation of a knob awkwardly disposed below the seat to adjust an initial deflection of a compression spring. This adjustment is time consuming and laborious.
The light user sitting in a chair previously adjusted to suit a heavy user must adjust the chair from the increased resistance set for the heavy user to the lesser resistance appropriate to the light user by numerous rotations of the adjustment knob. The same is true of a single user desiring to adjust from the increased resistance he desired for a meeting to the decreased resistance sought for reclining during a conference call. In these and other circumstances requiring large adjustments in pivoting resistance, the user of a seat with a prior art pivoting mechanism must either undertake the tedious adjustment process or forego the desired support characteristics.
With a knowledge of the foregoing, the present inventor has appreciated that a pivoting mechanism capable of enabling rapid, gross resistance adjustment between multiple resistance zones and, potentially, fine resistance adjustment within each given resistance zone would represent a marked advance in the art.